1. Field of the Invention
The present invention relates generally to automated monitoring devices, and particularly to a fastener tension monitoring system, particularly for monitoring threaded bolts, that generates electrical energy from forces imparted to the fastener and uses the energy to transmit data regarding those forces.
2. Description of the Related Art
Large structures (such as buildings, bridges, factories and manufacturing plants, ships, aircraft, etc.) are conventionally assembled using tensile fasteners, such as bolts, among other assembly means. A great deal of knowledge has been accrued over the years regarding the sizes and types of fasteners required for any given structure, and the gripping force that must be provided by the fasteners to provide a safe and sound structure.
While the structures and fasteners may be assembled properly during the construction process, various conditions act upon structural joints over time to cause the fasteners to loosen. Vibration due to traffic (on bridges) and the operation of associated machinery can act to loosen bolts and rivets in the structure. Corrosion can reduce the strength of a fastener and/or the adjacent structural material in a structure. The fastener itself may stretch slightly over time, resulting in a loosened joint.
As a result periodic inspections are required of many, if not most, large structures to detect any substandard joints or connections, and to repair those joints or connections as required. Such inspections are, of course, costly in terms of man-hours, and often require the operation of the structure to be shut down during the course of the inspection. This is particularly true of ships and aircraft, but may also hold true for various factories, manufacturing plants, pipelines, and similar structures, depending upon the depth of the inspection required. In most cases such inspections will not turn up any problems, with problems that are detected normally being a small minority of the total structural assembly. Nevertheless, the time required to perform the inspection, and the time lost from being unable to use the structure, remain the same whether problems are found or not.
Thus, a fastener tension monitoring system solving the aforementioned problems is desired.